Tidmouth Bay is a station and castle located on Toby's Branch Line near the old mine. It only appeared in the fifth and sixth series and in stock footage in the seventh series. The castle was found by Toby and Sir Topham Hatt after his grandchildren Stephen and Bridget showed him a map featuring the castle.
- The station reuses models of Maithwaite's station building and Maron's island platform canopy.
- During the sixth series, this set was referred to as 'Castle Station'. Signs were planned for the platforms, but never completed.
- Concept art for King of the Railway shows that Tidmouth Bay would have appeared as the railway station for Ulfstead Castle. This was never used in the final special for unknown reasons.
- In the book Christmas in Wellsworth, Tidmouth Bay is used to depict Rolf's Castle.